Lewis & Short

prō-tūbĕro, āre, v. n., to swell or bulge out, to grow forth (late Lat.), Sol. 45: poma, id. 46 fin.

    1. 2. Trop.: densa ne supra modum protuberent, Aus. Idyll. 13, praef. § 8; cf. id. ib. 16, 10.